Worst service ever

Worst service I ever paid for in my life. I started this service a month ago and since the router and the SIM card arrived, I've been having issues. Either the Wi-Fi light turns off or the whole router turns off and reboots itself. I've logged many complaints and they said the problem was with MTN. They then logged a fault with MTN and said that the problem should be solved in 48h. After 4 days I had to call them to hear that MTN hadn't rep**** about the problem and that they would call me back with an answer. Nobody called back, ever! I had to call them now and finally the lady I was chatting to said the problem is on my router (which I mentioned in the beginning); I had said to her that my airtime might run out and asked if she could call me back to finish the procedure to order a new router, she said yes sure. The call drops AND SHE DOESNT CALL ME BACK!! now what? Must I call again to speak to a different person and go through all again? I WANT A SOLUTION!!!